Rotor wheel fan blade adjusting apparatus for turbojet engines and the like

ABSTRACT

A fan blade adjusting apparatus for adjusting fan blades on a rotor wheel of a turbojet engine of the type having compressor blades and fan blades arranged radially spaced from one another on a common rotatable rotor wheel with the compressor blades supplying air to a primary flow duct of the engine and with the fan blades supplying air to a secondary flow duct of the engine. Piston-cylinder arrangements are arranged in the annular space between the primary and secondary flow ducts for imparting axial movement to an annular member attached by way of pivotal arms to the fan blades such that axial movement of the annular member effects pivotal adjustment of the fan blades. The annular member is attached to and rotatable with the rotor wheel and the forces are transferred from the piston-cylinder arrangement by way of an antifriction bearing having the outer race rotatably fixed but axially movable by way of the piston-cylinder arrangement and an inner race which moves rotatably and axially with the annular member. The fixed casing of the engine in the annular space includes guide elements and open spaces for permitting axial movement of the bearing and associated structure while radially supporting same.

United States Patent [191 Wildner Mar. 4, 1975 1 ROTOR WHEEL FAN BLADEADJUSTING APPARATUS FOR TURBOJET ENGINES AND THE LIKE [75] Inventor:Walter Wildner, Munich, Germany [731 Assignee: Motoren-undTurbinen-Union Munchen GmbH, Munich, Germany [221 Filed: Feb. 19, 1974[21] Appl. No.: 443,189

[30] Foreign Application Priority Data Primary E.\'aminerHenry F.Raduazo Attorney, Agent, or FirmCraig & Antonelli [57] ABSTRACT A fanblade adjusting apparatus for adjusting fan blades on a rotor wheel of aturbojet engine of the type having compressor blades and fan bladesarranged radially spaced from one another on a common rotatable rotorwheel with the compressor blades supplying air to a primary flow duct ofthe engine and with the fan blades supplying air to a secondary flowduct of the engine. Piston-cylinder arrangements are arranged in theannular space between the primary and secondary flow ducts for impartingaxial movement to an annular member attached by way of pivotal arms tothe fan blades such that axial movement of the annular member effectspivotal adjustment of the fan blades. The annular member is attached toand rotatable with the rotor wheel and the forces are transferred fromthe piston-cylinder arrangement by way of an antifriction bearing havingthe outer race rotatably fixed but axially movable by way of thepiston-cylinder arrangement and an inner race which moves rotatably andaxially with the annular member. The fixed casing of the engine in theannular space includes guide elements and open spaces for permittingaxial movement of the bearing and associated struc ture while radiallysupporting same.

17 Claims, 3 Drawing Figures Feb. 16, 1973 Germany 2307656 US. Cl415/130, 416/157, 60/226 R Int. Cl. FOld 7/00 [58] Field of Search..415/129,130,141,140; 416/157. 156, 162, 166; 60/226 R [56] ReferencesCited UNITED STATES PATENTS 1,942,100 1/1934 Houston 416/162 3,467,1989/1969 Ellinger 416/157 3,468,473 9/1969 Davies et a1. 415/129 3,472,32110/1969 Ellinger 415/130 3,476,486 11/1969 Davies eta]. 415/1293,549,272 12/1970 Bauger et a1 416/166 3,720,060 3/1973 Davies et al.415/79 PATENTED 3.869221 SHEET 2 OF 3 PATENTED 3,869 221 sum 3 or 3ROTOR WHEEL FAN BLADE ADJUSTING APPARATUS FOR TURBOJET ENGINES AND THELIKE BACKGROUND AND SUMMARY OF THE INVENTION This invention relates toapparatus for varying or adjusting the inclination of fan blades on aturbojet engine rotor wheel of the type designed to pass differentconcentric mass flows.

In modern turbojet engines a greater portion of the available enginethrust is frequently provided by axialflow fans of relatively largediameter.

The use of these axial-flow fans permits bypass ratios relative to thecore engine unit of the respective jet engine to be achieved as high as:1 or over.

With such bypass ratios a particularly useful practice has been to adaptthe fan to the changed conditions at cruise flight by making theinclination of the fan blades variable and thus optimize efficiencywithout adversely affecting the operating characteristics of the coreengine unit. A further objective of the variable fan blades has been toachieve reverse thrust by giving the fan blade contours a negativepitch.

The construction of apparatus for varying the fan blades hasnevertheless given considerable trouble from the design aspect in thatthe variable outer row of rotor blades of an axial-flow fan normallyforms an integral part of the basic engine unit, particularly so inconstructions where the variable outer fan blades and an inner row ofrotor blades of a compressor of the basic engine are mounted on a singlerotor wheel.

According to the teaching of a French Pat. No. 2,046,297, the fan rotorblades of a turbojet engine are made variable by means of a complexplanetary gearset within a central body arranged immediately aft of thehub of the compressor of the basic engine unit, where at least one towershaft extends from the planetary gearset and through the primary flowduct of said compressor to transmit the actuating movement of thegearset to the fan blades via further gearsets disposed in the spaceintervening between the primary duct and the secondary duct. Apart fromthe complexity of construction as a result of the particular arrangementof the actuating gear and of the plurality of intermediate drivesbetween the variable fan rotor blades this arrangement exhibits afurther disadvantage in that uniform and direct transmission of thenecessary actuating moment to the fan blades is not adequately ensured.

The present invention contemplates providing improved apparatus foradjusting the fan rotor blades of a rotor wheel of the type havingdifferent rows of blades along a radial stacking line, especially foruse with turbojet engines of multiflow construction, such that directtransfer of the actuating force from the drive system to the fan bladesis ensured in a relatively uncomplicated fashion. Additionally, theapparatus enables uniform transfer of the actuating moment to beachieved in all selectable positions of the fan blades. The drive systemand the actuating system of said apparatus furthermore economize spaceboth by construction and arrangement.

The present invention more particularly contemplates arranging theapparatus for adjusting the fan blades between a primary flow ductextending coaxially to the rotor wheel axis and a secondary flow duct,and

to provide said apparatus with a bearing arranged coaxially to the rotorwheel axis for axial sliding movement within fixed recesses in a fixedengine casing, where the blade actuating force is transmitted to theouter bearing race of said bearing while the inner race of said bearingis connected with an annular member which is arranged coaxially to therotor wheel axis and is coupled with blade stems of pivotally mountedfan rotor blades via actuating levers.

The present invention provides an advantage over previously disclosedsolutions in that it permits the necessary blade actuating force to betransmitted directly and in a surprisingly simple fashion from a fixedlymounted actuating means (hydraulically or pneumatically operatedactuating cylinders) to the fan blades through the operably rotatingrotor wheel.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawings which show, for purposes of illustration only, a single embodiment in accordance with thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial longitudinalsectional view which substantially illustrates a preferred embodiment ofthe present invention;

FIG. 2 is a partial front view taken along line ll-ll of FIG. 1 whichillustrates details of a pair'of variable fan blades arranged on a rotorwheel in accordance with FIG. 1, with parts broken away for clarity; and

FIG. 3 is a partial top schematic view (horizontal development of a viewtaken in direction of arrow III of FIG. 1) which illustrates details ofthe apparatus of this invention on a portion of a rotor wheel.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a portion of arotor-wheel l for use in a turbojet engine of multiflow construction.The rotor wheel 1 exhibits an inner row of compressor rotor blades 2which are arranged coaxially to the longitudinal axis A of the rotorwheel and which discharge compressed air into a primary flow duct 3 ofthe core engine unit. The rotor wheel 1 is externally provided with aplurality of'circumferentially equally spaced variable fan blades 4which discharge compressed air into a secondary flow duct 5 whichextends coaxially to the produced axis of the rotor wheel orlongitudinal centerline of the engine. Since details of the: remainderof a turbojet engine with which the present disclosure is associatedwill be readily understood by one skilled in the art, given the presentinvention, such details have not been included herein in order not toobscure the invention. In this connection, the air passing through flowduct 3 will serve as combustion air for a combustion chamber arrangeddownstream thereof, and jet exhaust nozzle means and/or propeller rotormeans as well as turbine means to drive the rotor wheel will be poweredby exhaust gases from the combustion chamber.

Reference numeral 6 generally indicates the bearing and retainingprovisions for the fan blades 4.

The apparatus for varying the fan blades 4 is arranged within an annulus7 formed between the primary flow duct 3 and the secondary flow duct 5.

The apparatus includes a plurality of equally circumferentially spacedactuating cylinders 8 which are arranged concentrically to axis A withinthe annulus 7 and which contain hydraulically or pneumatically operatedactuating pistons for sliding movement relative to the cylinders 8.

The actuating cylinders 8 are attached to a fixed portion 9 of theengine casing.

It is also contemplated by the present invention to utilizeelectromagnetically operable means (e.g. solenoids) of conventionaldesign in place of the actuating cylinders and pistons.

Connected to the actuating pistons and extending from the actuatingcylinders 8 are piston rods 10 which connect, through ring elements 11,12 and 13, to outer race 14 of a bearing 15 (antifriction bearing) whichextends coaxially to the production of the rotor wheel axis orlongitudinal centerline A of the engine.

A further ring element, 16, is fixedly connected with portion 9 of thecasing and envelopes with its axially directed portions 17, 18 a portion18 of ring 12 on the one side and inner race 19 of the bearing 15 on theother. A portion 20 of the ring element 16 further provides axiallydirected ways or guide slots 21 for engagement with teeth 21' on thering element 13 which is connected with the outer race 14 of the bearing15.

With this arrangement, the bearing 15 is flexibly radially supported andrecesses 22, 23 are formed in the casing to permit the bearing 15 toslide axially.

For transmission of the force needed for varying the fan blades 4 fromthe bearing 15 via the rotor wheel 1 which rotates when the jet engineis in operation, the inner bearing race 19 which invariably rotatestogether with the rotor wheel is connected with an annular member 24which extends coaxially to the axis A of the rotor wheel. Bladeadjusting forces are transmitted from rod 10 to inner race 19 by way ofmember 13 axially moving outer race 14 with consequent axial movement ofinner race 19.

With reference now to FIG. 3 which illustrates the apparatus of thepresent invention in horizontal development, the annular member 24exhibits equally spaced protuberances 25 which connect to actuatinglevers 27 (FIG. 2) of the fan blades 4 via articulated bearings 26.

Using contours drawn in solid and dash-dotted line, FIG. 3 furtherillustrates two different positions of the fan blades 4 as a result ofan actuating movement of the annular member 24 from left to rightaccompanied by an analogous change in the position of the protuberances25. (Right most position of member 24, and corresponding position ofblades 4, depicted in dashdotted lines and left most position depictedin solid lines.) In FIG. 3, each of the sets of piston-cylinderarrangements and associated linking structure to annular member 24 areshown in schematic form as control apparatus C, with two such controlapparatus C being depicted to indicate a plurality of same equallycircumferentially spaced about axis A.

As best illustrated in FIG. 1, the fan blades 4 are each radiallysupported by their stem 28 within an annular bearing support 29. Foraxial support and absorption of the centrifugal forces acting on theblades during rotation of the rotor wheel 1, use is made of a needlebearing 31 arranged between a rotationally symmetrical step on therespective blade stem 28 and the bearing support 29. Radially inwardextensions 29A of support 29 are connected to extensions 2A ofcompressor rotor blades 2 by pins 40.

The above-described apparatus of the present invention is alsocontemplated for use with jet engine configurations where the respectivelongitudinal centerline of a fan rotor wheel does not coincide with thelongitudinal centerline of the core, engine unit.

The apparatus of the present invention may also be used in conjunctionwith a rotor wheel which serves the function of an aft fan of a jetengine, said rotor wheel conceivably being provided with an inner row ofturbine rotor blades arranged concentrically to the axis of the rotorwheel and being driven by the gas flow from the core engine unit.

It is furthermore contemplated by this invention that the apparatus ofthis invention be used for axial-flow fan rotors of lift engines inpancake construction.

Although the most preferred embodiments relate to turbojet engines, thepresent invention also contemplates utilization of the apparatus foradjusting fan blades in other fluid flow machines having a single rotorwheel with two sets of blades supplying two separate ducts and with atleast one set of the blades being adjustable.

While I have shown and described several cmbodiments in accordance withthe present invention, it is understood that the same is susceptible ofnumerous changes and modifications as known to those skilled in the artand I therefore do not wish to be limited to the details shown anddescribed herein but intend to cover all such changes and modificationsas are encompassed by the scope of the appended claims.

I claim:

1. Fan blade adjusting apparatus for adjusting fan blades on a rotorwheel of a fluid flow machine of the type having compressor blades andfan blades circumferentially around said compressor blades 'on a commonrotatable rotor wheel with the compressor blades supplying fluid to aprimary flow duct of the flow machine and with the fan blades supplyingfluid to a secondary flow duct of said flow machine; said apparatuscomprising:

bearing means including an inner bearing race, an

outer bearing race, and antifriction means interposed between said innerand outer races for permitting relative rotation of said races withrespect to one another about the axis of rotation of the rotor wheel,

actuating force applying means engageable with one of said inner andouter races for axially moving said bearing means,

actuating force transmitting means connected to and movable with theother of said inner and outer races,

and coupling means for coupling said transmitting means to said fanblades such that axial movement of said transmitting means effectspivotal adjustment of said fan blades about fan blade pivot axesextending transverse to said axis of rotation of the rotor wheel.

2. Apparatus according to claim 1, wherein said primary and secondaryflow ducts extend coaxially to said axis of rotation of the rotor wheel,and wherein said bearing means, actuating force applying means, andactuating force transmitting means are disposed in an annular spacebetween said primary and secondary flow ducts.

3. Apparatus according to claim 1, wherein said flow machine includes afixed casing, wherein said force applying means includes a first portionfixed to said casing and a second portion which is connected to said oneof said inner and outer races and is axially movable with respect tosaid fixed portion.

4. Apparatus according to claim 3, wherein relatively fixed axiallyextending guide means are connected to said fixed casing for slidablyguiding axial movement of said bearing means while also radiallyflexibly supporting said bearing means.

5. Apparatus according to claim 4, wherein said second portion includesring elements which engage axially facing shoulders of said one of saidinner and outer races, and wherein an extension of one of said ringelements includes way means which are axially slidably guided in teethmeans of said fixed guide means.

6. Apparatus according to claim 5, wherein said fixed guide meansincludes guide extensions positioned radially inwardly and outwardly ofthe respective inner and outer races for radially guiding said bearingmeans and for forming recess means accommodating axial movement of saidbearing means.

7. Apparatus according to claim 1, wherein said actuating force applyingmeans is engageable with said outer race and said transmitting means isconnected to and movable with said inner race.

8. Apparatus according to claim 7, wherein said actu ating forceapplying means includes a piston and cylinder movable with respect toone another, with one of said piston and cylinder being attached to afixed casing of the flow machine and the other of said piston andcylinder being connected to said outer race for movement therewith.

9. Apparatus according to claim 1, wherein said flow machine is aturbojet engine, said primary flow duct leading to combustion chambermeans of said engine and said secondary flow duct being arranged inbypassing relationship to said primary flow duct for applying thrustforces to said engine.

10. Apparatus according to claim 9, wherein said fan blades are arrangedradially outwardly of said compressor blades and are pivotal about saidpivot axes independently of the compressor blades.

11. Apparatus according to claim 6, wherein said flow machine is aturbojet engine, said primary flow duct leading to combustion chambermeans of said en gine and said secondary flow duct being arranged inbypassing relationship to said primary flow duct for applying thrustforces to said engine.

12. Apparatus according to claim 9, wherein said ac- 5 tuating forceapplying means includes a piston and cylinder movable with respect toone another, with one of said piston and cylinder being attached to afixed casing of the flow machine and the other of said piston andcylinder being connected to said outer race for movement therewith.

13. Apparatus according to claim 1, wherein said transmitting meansincludes an annular member. wherein said fan blades include actuatinglevers ex tending radially with respect to their respective blade pivotaxes, and wherein said actuating levers are connected to said annularmember by way of articulated bearings such that axial movement of saidannular member results in pivotal movement of said actuating levers.

14. Apparatus according to claim 1, wherein said actuating forceapplying means includes one of hydraulic operated means, pneumaticallyoperated means and electromagnetic operated means.

15. Apparatus according to claim 1, wherein said actuating forceapplying means includes a plurality of fluid operated piston-cylindersystems which extend parallel to said axis of rotation of the rotorwheel and which are spaced circumferentially equally from one anotherabout said axis.

16. Apparatus according to claim 10, wherein said transmitting meansincludes an annular member. wherein said fan blades include actuatinglevers extending radially with respect to their respective blade pivotaxes, and wherein said actuating levers are connected to said annularmember by way of articulated bearings such that axial movement of saidannular member results in pivotal movement of said actuating levers.

17. Apparatus according to claim 16, wherein said actuating forceapplying means includes a plurality of fluid operated piston-cylindersystems which extend parallel to said axis of rotation of the rotorwheel and which are spaced circumferentially equally from one

1. Fan blade adjusting apparatus for adjusting fan blades on a rotorwheel of a fluid flow machine of the type having compressor blades andfan blades circumferentially around said compressor blades on a commonrotatable rotor wheel with the compressor blades supplying fluid to aprimary flow duct of the flow machine and with the fan blades supplyingfluid to a secondary flow duct of said flow machine; said apparatuscomprising: bearing means including an inner bearing race, an outerbearing race, and antifriction means interposed between said inner andouter races for permitting relative rotation of said races with respectto one another about the axis of rotation of the rotor wheel, actuatingforce applying means engageable with one of said inner and outer racesfor axially moving said bearing means, actuating force transmittingmeans connected to and movable with the other of said inner and outerraces, and coupling means for coupling said transmitting means to saidfan blades such that axial movement of said transmitting means effectspivotal adjustment of said fan blades about fan blade pivot axesextending transverse to said axis of rotation of the rotor wheel. 2.Apparatus according to claim 1, wherein said primary and secondary flowducts extend coaxially to said axis of rotation of the rotor wheel, andwherein said bearing means, actuating force applying means, andactuating force transmitting means are disposed in an annular spacebetween said primary and secondary flow ducts.
 3. Apparatus according toclaim 1, wherein said flow machine includes a fixed casing, wherein saidforce applying means includes a first portion fixed to said casing and asecond portion which is connected to said one of said inner and outerraces and is axially movable with respect to said fixed portion. 4.Apparatus according to claim 3, wherein relatively fixed axiallyextending guide means are connected to said fixed casing for slidablyguiding axial movement of said bearing means while also radiallyflexibly supporting said bearing means.
 5. Apparatus according to claim4, wherein said second portion includes ring elements which engageaxially facing shoulders of said one of said inner and outer races, andwherein an extension of one of said ring elements includes way meanswhich are axially slidably guided in teeth means of said fixed guidemeans.
 6. Apparatus according to claim 5, wherein said fixed guide meansincludes guide extensions positioned radially inwardly and outwardly ofthe respective inner and outer races for radially guiding said bearingmeans and for forming recess means accommodating axial movement of saidbearing means.
 7. Apparatus according to claim 1, wherein said actuatingforce applying means is engageable with said outer race and saidtransmitting means is connected to and movable with said inner race. 8.Apparatus according to claim 7, wherein said actuating force applyingmeans includes a piston and cylinder movable with respect to oneanother, with one of said piston and cylinder being attached to a fixedcasing of the flow machine and the other of said piston and cylinderbeing connected to said outer race for movement therewith.
 9. Apparatusaccording to claim 1, wherein said flow machine is a turbojet engine,said primary flow duct leading to combustion chamber means of saidengine and said secondary flow duct being arranged in bypassingrelationship to said primary flow duct for applying thrust forces tosaid engine.
 10. Apparatus according to claim 9, wherein said fan bladesare arranged radially outwardly of said compressor blades and arepivotal about said pivot axes independently of the compressor blades.11. Apparatus according to claim 6, wherein said flow machine is aturbojet engine, said primary flow duct leading to combustion chambermeans of said engine and said secondary flow duct being arranged inbypassing relationship to said primary flow duct for applying thrustforces to said engine.
 12. Apparatus according to claim 9, wherein saidactuating force applying means includes a piston and cylinder movablewith respect to one another, with one of said piston and cylinder beingattached to a fixed casing of the flow machine and the other of saidpiston and cylinder being connected to said outer race for movementtherewith.
 13. Apparatus according to claim 1, wherein said transmittingmeans includes an annular member, wherein said fan blades includeactuating levers extending radially with respect to their respectiveblade pivot axes, and wherein said actuating levers are connected tosaid annular member by way of articulated bearings such that axialmovement of said annular member results in pivotal movement of saidactuating levers.
 14. Apparatus according to claim 1, wherein saidactuating force applying means includes one of hydraulic operated means,pneumatically operated means and electromagnetic operated means. 15.Apparatus according to claim 1, wherein said actuating force applyingmeans includes a plurality of fluid operated piston-cylinder systemswhich extend parallel to said axis of rotation of the rotor wheel andwhich are spaced circumferentially equally from one another about saidaxis.
 16. Apparatus according to claim 10, wherein said transmittingmeans includes an annular member, wherein said fan blades includeactuating levers extending radially with respect to their respectiveblade pivot axes, and wherein said actuating levers are connected tosaid annular member by way of articulated bearings such that axialmovement of said annular member results in pivotal movement of saidactuating levers.
 17. Apparatus according to claim 16, wherein saidactuating force applying means includes a plurality of fluid operatedpiston-cylinder systems which extend parallel to said axis of rotationof the rotor wheel and which are spaced circumferentially equally fromone another about said axis.